Distinguishing Characteristics

Small sandpiper (13–15 cm long; 21–32 g).  Black legs with small webs between toes. Bill black, deep at base, usually straight and blunt tipped, sometimes slightly decurved at tip. Narrow but distinct white wing bar; black center of rump and tail. Sexes similar in plumage, but females average slightly larger, especially in bill length. Marked seasonal variation in plumage, and juveniles distinctive. Field identification often difficult (Veit and Jonsson 1984, Hayman et al. 1986). Of several small Calidris, most similar is Western Sandpiper (C. mauri), which also has small webs between toes. Bill of Western averages longer, often with slightly decurved tip, but plumages of the two species very similar. In Alternate (breeding) plumage, Semipalmated generally duller above and less extensively marked on flanks. In Juvenal plumage, Western shows contrast of rusty and gray above, especially on scapulars, while Semipalmated is more uniformly brownish-gray above. Basic (winter) plumages of the two virtually identical. Two Palearctic species, Rufous-necked Stint (C. ruficollis) and Little Stint (C. minuta), both rare in North America, very similar to Semipalmated in Juvenal and Basic plumages but lack webs between toes.